On Wed, Dec 01, 2004 at 09:40:53PM -0500, Ken Smith wrote: > On Thu, Dec 02, 2004 at 10:48:43AM +1000, Joel Hatton wrote: > > > I'm backing up a 5.x machine at the moment with this command: > > > > dump -0Lau -b128 -f - /var | gzip -2 | ssh FreeBSD4 dd of=aacd0s1f.gz > > > > After the dump finishes, I try to read the file on the 4.x destination: > > > > # gzip -dc aacd0s1a.gz | restore -ivf - > > Verify tape and initialize maps > > Tape is not a dump tape > > > > I can scp the file back to the 5.x machine and it loads just fine, so what > > gives? This type of failure is somewhat scary for me right now, given that > > I may have to restore files to another destination that may not be 5.x > > based. > > This is, unfortunately, something that you should not expect to work > for any *nix variant. The dump mechanism of creating backups creates > output that has "intimate knowledge" of the filesystem so that it can > recreate that filesystem exactly as it exists on the disk. As the > filesystem itself evolves (has features added to it) the dump programs > need to have their data structures change to accomodate the extra > information that is now needed. For example if in 4.X there were no > ACLs but 5.X added ACLs then the dump program's data structures would > need to be changed so it had the ability to store the ACL information > in the output, and the restore program would need to be modified to > look for that and do the right thing if it finds ACL information. > > If there had been no filesystem changes between 4.X and 5.X then > there would not be any need to change dump, and what you are trying > to do would work. But there were filesystem changes between 4.X and > 5.X, so dump was changed, and now there is extra stuff in the dump > images that the 4.X version of restore doesn't understand. This same > general principle holds for all OS's, not just FreeBSD.
Should I expect a dump taken from 4.X to be restorable on 5.X though? (I do). Ceri -- Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Einstein (attrib.)
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